In known solutions for locking systems for a male part and a female part, the locking element is often a separate ring. The ring may be located on either the male part or the female part, whilst the other part comprises a locking groove. The ring is compressed or expanded as the male part is passed into the female part, before it slips into place in the locking groove.
For example, air brake systems on commercial goods vehicles use connectors with nipples for the pipes, the connectors being made with male parts for connecting them to openings in female parts on another connector in a sealing manner. The nipples may have external, circumferential grooves onto which the pipes are pressed and secured. Opposite the nipples, the connector may have a male part with sealing elements and locking rings that are to secure the connectors in female parts which have internal locking ring grooves. A common type of locking ring is a split ring, optionally with a bevelled outer edge for facilitating insertion into the female part. As sealing elements it is usual to use O-rings, which can be stretched to be passed into the male parts and fitted in the annular grooves therein, or which are inserted into the female parts and located in internal grooves therein.
Thus, the locking rings are separate parts, which are mounted in the male parts or in the female parts before these parts are connected together.
Connectors of this type have long been made of metal, especially of brass, and the method of production has been turning. For reasons of price, it has been desirable to manufacture the connectors by injection moulding plastic in order to reduce material costs and to avoid machining. Moreover, it is also desirable to avoid separate locking rings.
A prerequisite for rational moulding is that the mould parts used, including the core which forms the inner space in the female part, should be capable of being used for a large number of connectors, and consequently the connectors must releasable from the mould parts without the mould parts having to be destroyed.
Furthermore, in many uses it is necessary to have the possibility of disconnecting the male part from the female part. For this purpose, it especially desirable to have a durable, good connection which can easily be disengaged using a suitable tool which is usually at hand in a workshop situation.
GB Patent No. 1521448 teaches a split coupling sleeve formed by punching and bending sheet metal so that the sleeve comprises four longitudinal wall portions separated by slits and a bottom having a hole for a tube. The sleeve is fitted on the outside of the tube, which is made having an external, circumferential locking bead against which an end of the sleeve comes to rest. At the opposite end, the sleeve has interior locking tangs which project obliquely into the sleeve. The locking tangs are attached to the rest of the sleeve close to the opposite end, and the free ends of the locking tangs point in the direction of insertion of a male part that is insertable into the sleeve. The male part is made having a collar which is locked by the locking tangs after having passed them, in that the free ends of the locking tangs remain resting against a transverse edge that delimits the collar. Thus, the sleeve is open in the slits between the four wall portions, and cannot contribute to the formation of a seal for a flowing medium. The sleeve has a solely mechanical function. Sealing is therefore formed between the tube and the male part. The sleeve is not suitable for moulding.
U.S. Pat. No. 5,988,704 teaches a coupling where a female part has locking tangs which can lock against an inserted male part. The female part is formed of several components, namely an outer sleeve of metal, a non-metallic tubular piece on which the sleeve is fitted and an inner sleeve of metal in which the locking tangs are formed, whilst the male part has transverse edges that come to rest against the ends of the locking tangs after insertion of the male part. A sealing ring is inserted in an annular groove in the sleeve.
U.S. Pat. No. 5,048,874 also teaches a coupling where a female part has inner locking tangs angled in the direction of insertion of a male part. The male part has a circumferential edge against which the ends of the locking tangs come to rest after insertion of the male part. The locking tangs are located on an inserted member in the female part, introduced into an elongate annular groove therein.
EP 1 333 217 also describes a coupling sleeve which can be made having integral locking tangs, and which in addition is equipped with an extra spring element for improving the resilience of the locking tangs.
Moreover, WO 96/24003 discloses a coupling sleeve having longitudinal integral locking tangs pointing towards the direction of insertion of a connecting member. The sleeve may contain a sealing element.